From: Florian Weimer <fweimer@redhat.com>
To: David Herrmann <dh.herrmann@gmail.com>,
Andy Lutomirski <luto@amacapital.net>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Ryan Lortie <desrt@desrt.ca>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Greg Kroah-Hartman <greg@kroah.com>,
John Stultz <john.stultz@linaro.org>,
Lennart Poettering <lennart@poettering.net>,
Daniel Mack <zonque@gmail.com>, Kay Sievers <kay@vrfy.org>,
Hugh Dickins <hughd@google.com>,
Tony Battersby <tonyb@cybernetics.com>
Subject: Re: [PATCH v3 0/7] File Sealing & memfd_create()
Date: Tue, 17 Jun 2014 11:54:17 +0200 [thread overview]
Message-ID: <53A01049.6020502@redhat.com> (raw)
In-Reply-To: <CANq1E4QQUKHabheq18AzkVZk3WDtAeC-6W66tVNB+EKgYOx1Vg@mail.gmail.com>
On 06/13/2014 05:33 PM, David Herrmann wrote:
> On Fri, Jun 13, 2014 at 5:17 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>> Isn't the point of SEAL_SHRINK to allow servers to mmap and read
>> safely without worrying about SIGBUS?
>
> No, I don't think so.
> The point of SEAL_SHRINK is to prevent a file from shrinking. SIGBUS
> is an effect, not a cause. It's only a coincidence that "OOM during
> reads" and "reading beyond file-boundaries" has the same effect:
> SIGBUS.
> We only protect against reading beyond file-boundaries due to
> shrinking. Therefore, OOM-SIGBUS is unrelated to SEAL_SHRINK.
>
> Anyone dealing with mmap() _has_ to use mlock() to protect against
> OOM-SIGBUS. Making SEAL_SHRINK protect against OOM-SIGBUS would be
> redundant, because you can achieve the same with SEAL_SHRINK+mlock().
I don't think this is what potential users expect because mlock requires
capabilities which are not available to them.
A couple of weeks ago, sealing was to be applied to anonymous shared
memory. Has this changed? Why should *reading* it trigger OOM?
--
Florian Weimer / Red Hat Product Security Team
next prev parent reply other threads:[~2014-06-17 9:54 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-13 10:36 [PATCH v3 0/7] File Sealing & memfd_create() David Herrmann
2014-06-13 10:36 ` [PATCH v3 1/7] mm: allow drivers to prevent new writable mappings David Herrmann
2014-07-09 8:55 ` Hugh Dickins
2014-07-19 16:12 ` David Herrmann
2014-06-13 10:36 ` [PATCH v3 2/7] shm: add sealing API David Herrmann
2014-07-16 10:06 ` Hugh Dickins
2014-07-19 16:17 ` David Herrmann
2014-06-13 10:36 ` [PATCH v3 3/7] shm: add memfd_create() syscall David Herrmann
2014-06-13 12:27 ` Michael Kerrisk (man-pages)
2014-06-13 12:41 ` David Herrmann
2014-06-13 14:20 ` Michael Kerrisk (man-pages)
2014-06-13 16:20 ` John Stultz
2014-06-16 4:12 ` Michael Kerrisk (man-pages)
2014-07-08 18:39 ` David Herrmann
2014-06-15 10:50 ` Jann Horn
2014-07-16 10:07 ` Hugh Dickins
2014-07-19 16:29 ` David Herrmann
2014-06-13 10:36 ` [PATCH v3 4/7] selftests: add memfd_create() + sealing tests David Herrmann
2014-07-16 10:07 ` Hugh Dickins
2014-07-19 16:31 ` David Herrmann
2014-06-13 10:36 ` [PATCH v3 5/7] selftests: add memfd/sealing page-pinning tests David Herrmann
2014-07-16 10:08 ` Hugh Dickins
2014-07-19 16:32 ` David Herrmann
2014-06-13 10:36 ` [RFC v3 6/7] shm: wait for pins to be released when sealing David Herrmann
2014-07-16 10:09 ` Hugh Dickins
2014-07-19 16:36 ` David Herrmann
2014-06-13 10:36 ` [RFC v3 7/7] shm: isolate pinned pages when sealing files David Herrmann
2014-06-13 15:06 ` Andy Lutomirski
2014-06-13 15:27 ` David Herrmann
2014-06-13 17:23 ` Andy Lutomirski
2014-07-09 8:57 ` Hugh Dickins
2014-07-19 16:40 ` David Herrmann
2014-06-13 15:10 ` [PATCH v3 0/7] File Sealing & memfd_create() Andy Lutomirski
2014-06-13 15:15 ` David Herrmann
2014-06-13 15:17 ` Andy Lutomirski
2014-06-13 15:33 ` David Herrmann
2014-06-17 9:54 ` Florian Weimer [this message]
2014-06-17 10:01 ` David Herrmann
2014-06-17 10:04 ` Florian Weimer
2014-06-17 10:10 ` David Herrmann
2014-06-17 12:13 ` Florian Weimer
2014-06-17 13:26 ` David Herrmann
[not found] ` <CALCETrVpZ0vFM4usHK+tQhk234Y2jWzB1522kGcGvdQQFAqsZQ@mail.gmail.com>
2014-06-17 16:36 ` David Herrmann
2014-06-17 16:41 ` Andy Lutomirski
2014-06-17 16:51 ` David Herrmann
2014-06-17 17:01 ` Andy Lutomirski
2014-06-17 20:31 ` Hugh Dickins
2014-06-17 21:25 ` Andy Lutomirski
2014-07-08 16:54 ` David Herrmann
2014-07-09 8:53 ` Hugh Dickins
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